The present invention relates to an apparatus and method for assessing the status of a cellular pathway. Several biotechnology companies are developing DNA-chips which contain printed arrays of hundreds or thousands of genes, or more. However, the DNA sequence of the genes or the level of gene expression do not reflect the actual functional state of the proteins encoded by the genes. The functional state of each protein involves more than simply the amount of the proteins. It includes, for example, post translational modifications (phosphorylation, glycosylation, etc.), binding partners in cellular pathways, conformation, enzymatic function, and state of activation. Moreover, each cell in the body has a pattern of functional proteins which reflects the current biologic working state of the cell (e.g., growing, differentiating, diseased, dying, senescent, etc.). Therefore, there exists a need in the art for a device and method for determining the status of cellular pathways (e.g., the phosphorylation state or binding partners of involved proteins) in tissue samples, including human tissue samples, thus providing the diagnostician or clinician with an early warning of impending or occult toxicity, disease state, response to treatment, differentiated function, and so forth.